1. Field of the Invention
The present invention relates to a transmission apparatus for balance test operation, more particularly one, which includes a transmission gear and a clutch capable of engaging and disengaging the transmission gear, and which allows a teat to be carried out for finding out whether a work piece has been positioned in a balanced position before a machining action is started.
2. Brief Description of the Prior Art
Lathes are important machining apparatuses. Referring to FIG. 1, a currently existing vertical lathe 9 includes a supporting frame 91, cutting tools 92, two shutters 93, a rotating disk 94, and two working platforms 95. The cutting tools 92 are positioned in a holding space 911 of the supporting frame 91. The shutters 93 are pivoted to the supporting frame 91 for closing the holding space 911. Each of the working platforms 95 has several clamping jaws 951 for clamping work pieces. The working platforms 95 are moved into the holding space 911 of the supporting platform 91 in sequence by means of the rotating disk 94 such that the workpieces are machined by means of the cutting tools 92; before each cutting process is started, the shutters 93 will be closed to prevent cutting oil and iron bits from getting out of the holding space 911 to dirty the environment as well as preventing the work pieces from flying out and hurting people.
After the lathe finishes machining a work piece fixed on a working platform, this working platform will be moved out of the holding space 911 by means of the rotating disk 94, and next this working platform 95 will be firmly fixed to the supporting frame 91, and the clamping jaws of this working platform will release the work piece. Then, this work piece is removed from this working platform, and another work piece is positioned on this working platform, and clamped by means of the clamping jaws.
The above lathe structure has a disadvantage: when operating such a lathe, the operators can't carry out test operation to find out whether a work piece has been held in a balanced position on a working platform 95 by means of the clamping jaws 951. It isn't possible to find out whether a work piece is held in a balanced position until this work piece is moved into the holding space 911 together with a working platform 95, and the spindle makes this working platform 95 rotate together with it to carry out a balance test; if it is found out that this work piece isn't in a balanced position, this working platform 95 has to be moved out of the holding space 911, and this work piece released and repositioned, wasting much time. Or alternatively, the operator can rotate this working platform 95 manually to find out whether this work piece is held in its balanced position. However, it is difficult to find tiny abnormalities by means of manual testing. If a work piece is machined in an unbalanced position, the work piece will become damaged and useless, and even fly out to cause damage to the lathe and hurt people.